1. Field of the Invention
The present invention relates generally to optical positioning of a light beam and more particularly to two-dimensional optical positioning of a light beam.
2. Background Art
A number of optical switch technologies are currently used to control the optical passage of light. With one technology, electric current is applied to a polymer to create a thermal effect that changes a refractive index of a polymer. As the refractive index changes, a light beam passing through the polymer is selectively routed from an input to an output. Although faster than a comparable mechanical optical switch, the switching time of polymer optical switches is limited significantly by the thermal characteristics of the polymer. Additionally, the optical properties of the light transmitted through the polymer are undesirably affected by the optical characteristics of the polymer.
Another optical switch is disclosed by Leslie A. Field et al. in "The 8.sup.th International Conference on Solid-State Sensors and Actuators, and Eurosensors IX, Stockholm, Sweden, Jun. 25-29, 1995." The optical switch is micromachined in silicon and uses a thermally activated actuator to mechanically move a single send optical fiber relative to two receive optical fibers. Field et al. exhibits relatively slow mechanical movement due to inherent thermal effects. Additionally, Field et al. provides only one degree of optical alignment, resulting in inefficient transfer between optical fibers due to slight misalignments.
Another micromachined optical switch is disclosed by Levinson in U.S. Pat. No. 4,626,066. Levinson uses a cantilevered micromachined mirror that is electrostatically positioned between a stopped and unstopped position. While Levinson's mirror may deflect light between two optical fibers, as with the aforementioned switch designs, it also is capable of optical alignment in only one dimension.
Reflections of a diffracted impinging laser beam from a grooved surface may be used to maintain a one-dimensional position of the impinging diffracted laser beam relative to the grooved surface, for example, a position of an impinging laser beam on a grooved surface of a compact disk (CD) drive.
What is needed is an optical switch that provides fast and precise switching of light between one input and a plurality of outputs, or vice versa.